There are a few things to take into consideration in my opinion when it comes to this. How much trust do you have for the others that are helping manage the guild bank in general and do they account share. I never let anyone get anything from the last tab in the guild bank which had most of the rare/BiS gear. It wasn't really a trust issue it's just that the more people that have access the greater the opportunity of somehing happening. Account sharing, keyloggers etc. there are plenty of asshats out there that wouldn't think twice about jacking your gear. If your on your 19 a lot or in game in general it shouldn't really be a problem. You could even create a rank just below Guild Master to promote all your alts to so that you will still be the only one with access but will not have to change characters everytime someone needs something from the guild bank.
Since it is being funded by 5 80's i'm guessing that the majority of the players are xfers/re-rolls. In this case, ask yourself what you are willing to provide for them, considering they don't have a main. Will you provide Rum, Bandages, Speed Pots etc.? You may want to do this or you may want them to make a DK and get bandages themselves. I agree that you may only need 2-3 tabs, depending on how much gear you want to lock down. We had a lot of gear so I had to purchase 5 tabs. And as previously stated, no sense in breaking apart stacks of items it just takes up more space and people can just drag and drop it to restack it then take the whole stack. My general thoughts would be.
Tab 1: Linen, Wool, Moss Agate etc. things for leveling proffesions which you will get tons of doing runs. Allow anyone to deposit things that may be helpful to others that you don't really mind if it goes missing.
Tab 2: RUM, RUM, RUM Depending on how often you want to make a rum run let that guide how many stacks they are limited to. (Pro Tip: If someone has engineering make them do the rum runs and use the portable mailbox, this will bypass running out of bag space and having to make multiple trips.)
Tab 3: Consumables that your willing to provide, Bandages, Speed Pots Etc., Lock it down depending on supply, if your guildies chug 10 speed pots a game and you can afford it by all means, if not then maybe limit it to 1 stack or something, or just fill it with bandages and save the pots for premades only.
Tab 4: Uncommon gear, 5/5 Pants, Forest Leather Bracers, Blood Ring etc. I'd let officers or whomever you trust dish this out to help in case your not on at least people can get mostly geared even when your not available. Enchant mats/scrolls if you have room.
Tab 5: Premade stuff (bombs, pots etc.) you could also throw enchant mats or scrolls here if need be. Trustworthy people with the ability to get out enough consumables in case you have a premade but can't be there, someone can still hand things out.
Tab 6: elite tab for BIS items only, SFs, ABs, highpriced items. I personally locked this tab down, you can allow people to view it and give it out as you see fit, they can whisper you or mail you however you want to run it. But as I said, I locked mine, not that I didn't trust people its just for the reasons I stated above.
